Neuromuscular Disorders USMLE Step 1 Practice Question
A 22-year-old man presents with recurrent episodes of generalized weakness beginning after rest following strenuous exercise. Episodes last 20-45 minutes and are associated with mild myotonia. Vital signs show HR 78/min, BP 128/82 mmHg, RR 16/min, temperature 37°C, SpO2 98%. Serum potassium is 5.8 mEq/L during an acute attack. Creatine kinase is normal. He denies recent medication use or similar family history. Which of the following is the most likely diagnosis?
Answer choices
- APolymyositis
- BBotulism
- CLambert-Eaton syndrome
- DALS
- EHyperkalemic periodic paralysisCorrect answer
- FHypokalemic periodic paralysis
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